Biomarkers in Post-kala-azar Dermal Leishmaniasis

Vaccine efficacy induced by virus-like particles containing Leishmania donovani surface glycoprotein GP63

Leishmania donovani surface glycoprotein 63 (GP63) is a major virulence factor involved in parasite escape and immune evasion. In this study, we generated virus-like particles (VLPs) expressing L. donovani GP63 using the baculovirus expression system. Mice were intramuscularly immunized with GP63-VLPs and challenged with L. donovani promastigotes. GP63-VLP immunization elicited higher levels of L. donovani antigen-specific serum antibodies and enhanced splenic B cell, germinal center B cell, CD4+, and CD8+ T cell responses compared to unimmunized controls. GP63-VLPs inhibited the influx of pro-inflammatory cytokines IFN-γ and IL-6 in the livers, as well as thwarting the development of splenomegaly in immunized mice. Upon L. donovani challenge infection, a drastic reduction in splenic parasite burden was observed in VLP-immunized mice. These results indicate that GP63-VLPs immunization conferred protection against L. donovani challenge infection by inducing humoral and cellular immunity in mice.

The Potential Use of Peptides in the Fight against Chagas Disease and Leishmaniasis

Chagas disease and leishmaniasis are both neglected tropical diseases that affect millions of people around the world. Leishmaniasis is currently the second most widespread vector-borne parasitic disease after malaria. The World Health Organization records approximately 0.7-1 million newly diagnosed leishmaniasis cases each year, resulting in approximately 20,000-30,000 deaths. Also, 25 million people worldwide are at risk of Chagas disease and an estimated 6 million people are infected with Trypanosoma cruzi. Pentavalent antimonials, amphotericin B, miltefosine, paromomycin, and pentamidine are currently used to treat leishmaniasis. Also, nifurtimox and benznidazole are two drugs currently used to treat Chagas disease. These drugs are associated with toxicity problems such as nephrotoxicity and cardiotoxicity, in addition to resistance problems. As a result, the discovery of novel therapeutic agents has emerged as a top priority and a promising alternative. Overall, there is a need for new and effective treatments for Chagas disease and leishmaniasis, as the current drugs have significant limitations. Peptide-based drugs are attractive due to their high selectiveness, effectiveness, low toxicity, and ease of production. This paper reviews the potential use of peptides in the treatment of Chagas disease and leishmaniasis. Several studies have demonstrated that peptides are effective against Chagas disease and leishmaniasis, suggesting their use in drug therapy for these diseases. Overall, peptides have the potential to be effective therapeutic agents against Chagas disease and leishmaniasis, but more research is needed to fully investigate their potential.

Adjuvantation of whole-killed Leishmania vaccine with anti-CD200 and anti-CD300a antibodies potentiates its efficacy and provides protection against wild-type parasites

One of the major reasons behind the limited success of vaccine candidates against all forms of leishmaniasis is the inability of parasitic antigens to induce robust cell-mediated immunity and immunological memory. Here we find, for the first time, that the adjuvantation of whole-killed Leishmania vaccine (Leishvacc) with anti-CD200 and anti-CD300a antibodies enhances CD4+ T cells mediated immunity in vaccinated mice and provides protection against wild-type parasites. The antibody adjuvantation, either alone or with a TLR4 agonist monophosphoryl A (MPL-A), induced the production of pro-inflammatory cytokines viz., IFN-γ, TNF-α, and IL-2 by antigen experienced CD4+ T cells, and also enhanced their rate of conversion into their memory phenotypes against Leishvacc antigens. The antibody adjuvanted vaccine also promoted the generation of IgG2a-mediated protective humoral immunity in vaccinated mice. Further, the mice vaccinated with antibodies adjuvanted vaccine showed strong resilience against metacyclic forms of L. donovani parasites as we observed reduced clinical features such as splenomegaly, hepatomegaly, granulomatous tissues in the liver, and parasitic load in their spleen. The findings of this study demonstrate that the anti-CD200 and anti-CD300a antibodies have potential to increase the protective efficacy of the whole-killed Leishmania vaccine, and opens up a new gateway to diversify the roles of immune checkpoints in vaccine development against leishmaniasis.

Therapeutic potential of rWnt5A in curbing Leishmania donovani infection

In view of the antagonism of Wnt5A signaling toward microbial pathogens, we were interested in evaluating the therapeutic potential of recombinant Wnt5A (rWnt5A) in curbing Leishmania donovani infection. Initially, using L. donovani-infected RAW 264.7 and peritoneal macrophages, we demonstrated that application of rWnt5A as opposed to the vehicle control to the infected cells significantly dampens L. donovani infection. Inhibition of infection was associated with increase in cell-associated reactive oxygen species (ROS), and blocked by the ROS production inhibitor diphenylene iodonium chloride (DPI). rWnt5A, but not the vehicle control (PBS: phosphate-buffered saline) administration to L. donovani-infected mice appreciably reduced the infection load, and inhibited disease progression as evident from the preservation of splenic white pulp architecture. rWnt5A administration, moreover, led to elevation of both cell-associated ROS and the activation of splenic T cells. Substantial increase in T cell-associated Interleukin-2 (IL-2) and Granzyme B (GRB) upon exposure of splenic lymphocytes harvested from rWnt5A-treated mice to L. donovani-infected RAW 264.7 macrophages in vitro validated the occurrence of L. donovani-responsive T cell activation in vivo. In summary, this study unveils the therapeutic potential of rWnt5A in curbing L. donovani infection and the progression of experimental visceral leishmaniasis possibly through increase in cellular ROS and T cell activation. Accordingly, it opens up a new avenue of investigation into the use of rWnt5A as a therapeutic agent for restraining the progression of drug-resistant L. donovani infection.

Immunoinformatics Approach to Design a Multi-Epitope Vaccine against Cutaneous Leishmaniasis

Cutaneous Leishmaniasis (CL), a neglected vector-borne disease caused by protozoan parasite Leishmania major (L. major), is a major public health concern, and the development of new strategies to reduce the disease incidence has become a top priority. Advances in immunoinformatics and in-silico epitope prediction could be a promising approach to designing a finest vaccine candidate. In this study, we aimed to design a peptide-based vaccine against CL using computational tools and identified ten B-cell-derived T-cell epitopes from the glycoprotein gp63 of L. major. All of the potential immunodominant epitopes were used to design a vaccine construct along with a linker and an adjuvant at the N-terminal for enhancing its immunogenicity. Additionally, many characteristics of the proposed vaccine were examined, and it was confirmed to be non-allergenic, non-toxic, and thermally stable. To assess the vaccine interaction with the innate immune toll-like receptor-4 (TLR-4), a 3D structure of the vaccine construct was developed. Molecular docking and molecular dynamic simulation were used to confirm the binding and to assess the stability of the vaccine-TLR4 complex and interactions, respectively. In conclusion, our multi-epitope vaccine will provide a gateway to analyze the protein function of a potential vaccine candidate against CL.

Case report: Diagnosis of visceral leishmaniasis using metagenomic next-generation sequencing and bone marrow smear

Visceral leishmaniasis (VL) is a chronic infectious disease transmitted by sandflies. The primary clinical manifestations are remittent fever, pancytopenia, and splenomegaly. As VL is rare with atypical symptoms, its diagnosis is often incorrect, missed, or delayed. Without appropriate treatment, the case fatality rate of symptomatic disease is more than 95%, but the prognosis is good if diagnosed and treated timeously. We report a case of VL that was diagnosed using metagenomic next-generation sequencing (mNGS) of a peripheral blood sample. By using mNGS and a bone marrow smear, we were able to make a timely diagnosis. The patient was treated with antimony, rapidly recovered, and was discharged from the hospital. This case illustrates the value of mNGS for making a timely diagnosis of VL.

Gauging the skin resident Leishmania parasites through a loop mediated isothermal amplification (LAMP) assay in post-kala-azar dermal leishmaniasis

Despite the availability of highly sensitive polymerase chain reaction (PCR)-based methods, the dearth of remotely deployable diagnostic tools circumvents the early and accurate detection of individuals with post-kala-azar dermal leishmaniasis (PKDL). Here, we evaluate a design-locked loop-mediated isothermal amplification (LAMP) assay to diagnose PKDL. A total of 76 snip-skin samples collected from individuals with probable PKDL (clinical presentation and a positive rK39 rapid diagnostic test (RDT)) were assessed by microscopy, qPCR, and LAMP. An equal number of age and sex-matched healthy controls were included to determine the specificity of the LAMP assay. The LAMP assay with a Qiagen DNA extraction (Q-LAMP) showed a promising sensitivity of 72.37% (95% CI: 60.91-82.01%) for identifying the PKDL cases. LAMP assay sensitivity declined when the DNA was extracted using a boil-spin method. Q-qPCR showed 68.42% (56.75-78.61%) sensitivity, comparable to LAMP and with an excellent agreement, whereas the microscopy exhibited a weak sensitivity of 39.47% (28.44-51.35%). When microscopy and/or qPCR were considered the gold standard, Q-LAMP exhibited an elevated sensitivity of 89.7% (95% CI: 78.83-96.11%) for detection of PKDL cases and Bayesian latent class modeling substantiated the excellent sensitivity of the assay. All healthy controls were found to be negative. Notwithstanding the optimum efficiency of the LAMP assay towards the detection of PKDL cases, further optimization of the boil-spin method is warranted to permit remote use of the assay.

Visceral leishmaniasis (kala-azar) caused by L. mexicana in a patient with AIDS

We describe a patient with HIV who presented with hemophagocytic lymphohistiocytosis and nonspecific abdominal imaging findings. He was diagnosed with visceral leishmaniasis via bone marrow biopsy and treated in the hospital with amphotericin B infusions. Despite pharmacologic interventions, including amphotericin and miltefosine in addition to antiretroviral therapy, our patient experienced multiple relapses and a challenging clinical course.

Development of Novel Anti-Leishmanials: The Case for Structure-Based Approaches

The neglected tropical disease (NTD) leishmaniasis is the collective name given to a diverse group of illnesses caused by ~20 species belonging to the genus Leishmania, a majority of which are vector borne and associated with complex life cycles that cause immense health, social, and economic burdens locally, but individually are not a major global health priority. Therapeutic approaches against leishmaniasis have various inadequacies including drug resistance and a lack of effective control and eradication of the disease spread. Therefore, the development of a rationale-driven, target based approaches towards novel therapeutics against leishmaniasis is an emergent need. The utilization of Artificial Intelligence/Machine Learning methods, which have made significant advances in drug discovery applications, would benefit the discovery process. In this review, following a summary of the disease epidemiology and available therapies, we consider three important leishmanial metabolic pathways that can be attractive targets for a structure-based drug discovery approach towards the development of novel anti-leishmanials. The folate biosynthesis pathway is critical, as Leishmania is auxotrophic for folates that are essential in many metabolic pathways. Leishmania can not synthesize purines de novo, and salvage them from the host, making the purine salvage pathway an attractive target for novel therapeutics. Leishmania also possesses an organelle glycosome, evolutionarily related to peroxisomes of higher eukaryotes, which is essential for the survival of the parasite. Research towards therapeutics is underway against enzymes from the first two pathways, while the third is as yet unexplored.

An In-depth Proteomic Map of Leishmania donovani Isolate from Post Kala-azar Dermal Leishmaniasis (PKDL) Patient

BACKGROUND

The trypanosomatid protozoan parasite Leishmania donovani is the etiological agent of visceral leishmaniasis (VL) or kala-azar. The patients that have undergone treatment may still harbor the parasite and in a small fraction of the patients the disease re-erupts in the form of post kala-azar dermal leishmaniasis (PKDL). PKDL is a pathological condition found to be intermediate between VL and complete cure of VL. The PKDL disease progression is determined by the host immune response to L. donovani. The majority of the proteomic studies on L. donovani till date have been undertaken on parasites either isolated from kala-azar patients or on established laboratory strains of L. donovani. However, no proteomic information is available on the cutaneous localized isolates of L. donovani from PKDL patients.

METHODS

The promastigote stage of L. donovani isolate from PKDL patient was cultured and harvested. The cell lysates were trypsin digested, followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. The LC-MS/MS raw data were analyzed on Proteome Discoverer. Further bioinformatics analysis was carried out.

RESULTS

In the present, we have used high-resolution mass spectrometry to map the global proteome of a L. donovani isolate from PKDL patient. This in-depth study resulted in the identification of 5537 unique proteins from PKDL isolate of L. donovani which covered 64% of its proteome.

OUTCOME

This study also identified proteins previously shown to be upregulated in PKDL L. donovani. This is the most in-depth proteome of Leishmania donovani parasite till date.

A Case of Leishmaniasis Infantum Kala-Azar in an Immunocompetent 49-Year-Old Man

An immunocompetent 45-year-old Cuban-American man presented with worsening knee pain and swelling despite antibiotic therapy. On physical examination, the patient was ill-appearing, cachectic, with a protuberant abdomen and massive splenomegaly. In addition, he had a 10 cm area of peripheral hyperemia with central necrosis in the medial left knee that was non-tender and non-fluctuant. Initial lab work demonstrated pancytopenia, hyponatremia, hypoalbuminemia, and anemia of chronic inflammation. Peripheral smear showed microcytic, hypochromic red blood cells with mild anisopoikilocytosis. and leukopenia with slight left shift and metamyelocytes. Bone marrow biopsy demonstrated amastigotes and kinetoplasts within white blood cells and extracellular space consistent with leishmaniasis. Centers for Disease Control and Prevention (CDC) testing with PCR returned positive for Leishmaniasis infantum. The patient received two courses of amphotericin B lipid complex (ABLC) with a 28-day course of miltefosine, which resulted in clinical improvement. This case illustrates the unique pathology that can affect immigrants and highlights the need to increase health provider awareness of foreign pathologies in areas with large migrant populations.

Precision Medicine in Control of Visceral Leishmaniasis Caused by L. donovani

Precision medicine and precision global health in visceral leishmaniasis (VL) have not yet been described and could take into account how all known determinants improve diagnostics and treatment for the individual patient. Precision public health would lead to the right intervention in each VL endemic population for control, based on relevant population-based data, vector exposures, reservoirs, socio-economic factors and other determinants. In anthroponotic VL caused by L. donovani, precision may currently be targeted to the regional level in nosogeographic entities that are defined by the interplay of the circulating parasite, the reservoir and the sand fly vector. From this 5 major priorities arise: diagnosis, treatment, PKDL, asymptomatic infection and transmission. These 5 priorities share the immune responses of infection with L. donovani as an important final common pathway, for which innovative new genomic and non-genomic tools in various disciplines have become available that provide new insights in clinical management and in control. From this, further precision may be defined for groups (e.g. children, women, pregnancy, HIV-VL co-infection), and eventually targeted to the individual level.

Advancement in leishmaniasis diagnosis and therapeutics: An update

Leishmaniasis is regarded as a neglected tropical disease by World Health Organization (WHO) and is ranked next to malaria as the deadliest protozoan disease. The primary causative agents of the disease comprise of diverse leishmanial species sharing clinical features ranging from skin abrasions to lethal infection in the visceral organs. As several Leishmania species are involved in infection, the role of accurate diagnosis becomes pivotal in adding new dimensions to anti-leishmanial therapy. Diagnostic methods must be fast, reliable, easy to perform, highly sensitive, and specific to differentiate among similar parasitic diseases. Herein, we present the conventional and recent approaches impended for the disease diagnosis and their sensitivity, specificity, and clinical application in parasite detection. Furthermore, we have also elaborated various new methods to cure leishmaniasis, which include host-directed therapies, drug repurposing, nanotechnology, and combinational therapy. This review addresses novel techniques and innovations in leishmaniasis, which can aid in unraveling new strategies to fight against the deadly infection.

[Generalized old world leishmaniasis: first Moroccan case in an immunocompetent adult?]

BACKGROUND

Post-kala-azar dermal Leishmaniasis (PKDL) is a rare skin syndrome observed after treatment of visceral Leishmaniasis (VL) with pentavalent antimonial organic salts, never described in Morocco before. Here we report a case in an immunocompetent adult.

CASE

A 36-year-old-man from Tata in southern Morocco, with a history of visceral Leishmaniasis 2 years before and treated with meglumine antimoniate and amphotericin B with good clinical course, was hospitalized in dermatology for an erythematous papulo-nodular closet of the face. Six months ago, he presented oral mucosa involvement, then 3 months later, cutaneous lesions appeared on the face. The dermatological examination revealed a papulo-nodular erythematous closet extending to the nose and both cheeks, crusty and lupoid lesions on the forehead, around the eyes and chin, associated with an ulcerative and painless lesion on the heeL. The examination of the oral mucosa revealed an ulceration of the posterior third of the tongue and a papillomatous aspect of the soft palate. The skin biopsy and smear found some amastigote forms of Leishmania bodies. ITS1 PCR was positive (genus Leishmania). The HIV serology was negative. The diagnosis of PKDL was then evoked. The patient received intra-muscular injections of meglumine antimoniate with good progress.

CONCLUSION

To our knowledge, this is the first case of generalised leishmaniasis suggesting PKDL reported in a Moroccan immunocompetent adult.

Genome wide comparison of Leishmania donovani strains from Indian visceral leishmaniasis and para-kala-azar dermal leishmaniasis patients

Visceral leishmaniasis (VL) or Kala-azar, primarily caused by Leishmania donovani, is a major health concern in many countries including India. Growing unresponsiveness among the parasites toward the available drugs is alarming, and so, it is necessary to decipher the underlying mechanism of such development for designing new therapeutics. Moreover, even after successful treatment, some VL patients develop apparently harmless skin lesions known as post-kala-azar dermal leishmaniasis (PKDL) which may serve as a reservoir of the parasite in the transmission cycle. Furthermore, recent reports of para-kala-azar dermal leishmaniasis (para-KDL) cases having PKDL manifestation with concomitant VL, emphasize the necessity of more attention to address complex nature of the parasite for eradicating the disease effectively. In the present study, whole genome sequencing is performed with sodium stibogluconate (SSG) sensitive and resistant L. donovani strains along with SSG sensitive para-KDL strains, derived from the clinical isolates of Indian patients to identify the genomic variations among them. Notably, the analyses of chromosome somy values and genome wide mutation profile in the coding regions reveal distinct clustering of the para-KDL strains with 24 genes being mutated uniquely in this group. Such distinguishing genomic changes among the para-KDL strains could be significant for the parasites to become dermatotropic. Overall, the study reveals a possible correlation of the development of SSG resistance and the transition towards the manifestation of PKDL with chromosome aneuploidy and non-synonymous genetic variations in the coding sequences of the L. donovani strains from Indian patients.

Development and Clinical Evaluation of Serum and Urine-Based Lateral Flow Tests for Diagnosis of Human Visceral Leishmaniasis

Visceral leishmaniasis (VL), a fatal parasitic infection, is categorized as being neglected among tropical diseases. The use of conventional tissue aspiration for diagnosis is not possible in every setting. The immunochromatography-based lateral flow assay (LFA) has attracted attention for a long time due to its ability to give results within a few minutes, mainly in resource-poor settings. In the present study, we optimized and developed the LFA to detect anti-Leishmania antibodies for VL diagnosis. The performance of the developed test was evaluated with serum and urine samples of Indian VL patients and Brazilian sera. The new test exploits well-studied and highly-sensitive purified antigens, LAg isolated from Leishmania donovani promastigotes and protein G conjugated colloidal-gold as a signal reporter. The intensity of the bands depicting the antigen-antibody complex was optimized under different experimental conditions and quantitatively analyzed by the ImageJ software. For the diagnosis of human VL in India, LFA was found to be 96.49% sensitive and 95% specific with serum, and 95.12% sensitive and 96.36% specific with urine samples, respectively. The sensitivity and specificity of LFA were 88.57% and 94.73%, respectively, for the diagnosis of Brazilian VL using patients' sera infected with Leishmania infantum. LFA is rapid and simple to apply, suitable for field usage where results can be interpreted visually and particularly sensitive and specific in the diagnosis of human VL. Serum and urine LFA may improve diagnostic outcomes and could be an alternative for VL diagnosis in settings where tissue aspiration is difficult to perform.

Cutaneous and Mucocutaneous Leishmaniasis

Leishmaniasis is a chronic disease caused by flagellate protozoa of the genus Leishmania. It is a global disease, but most cases are seen in South America, the Mediterranean, and some areas of Asia and Africa. The 3 main types of leishmaniasis are cutaneous (the most common), mucocutaneous, and visceral (the most severe). Visceral leishmaniasis is also known as kala-azar. Leishmaniasis is diagnosed by demonstrating the presence of Leishmania amastigotes in clinical specimens using direct microscopic examination or molecular analysis. Various treatments exist, although the evidence supporting the options available for cutaneous leishmaniasis is weak. Both the classical presentation of leishmaniasis and our management of the disease have changed in recent decades because of acquired immune deficiency caused by conditions such as human immunodeficiency infection or the use of tumor necrosis factor inhibitors.

Ocular Leishmaniasis - A systematic review

The incidence of leishmaniasis is reported to be up to 1 million per year. To date, there has been no comprehensive review describing the diversity of clinical presentations of ocular leishmaniasis (OL) and its treatment. This systematic review aims to address this knowledge gap and provide a summary of the clinical presentation, natural course, and treatment options for OL. Our study identified a total of 57 published articles as describing cases of OL involving: adnexa (n = 26), orbit (n = 1), retina (n = 7), uvea (n = 18) and cornea (n = 6). Though well described and easily treated, palpebral leishmaniasis is often misdiagnosed and may lead to chronic issues if untreated. The retinal manifestations of Leishmaniasis consist of self-resolving hemorrhages secondary to thrombocytopenia. Two main uveitis etiologies have been identified: uveitis in the context of active Leishmanial infection (associated with immunosuppression) and uveitis occurring as an immune reconstitution syndrome. Corneal involvement in most geographic areas generally follows an aggressive course, most often ending in corneal perforation if left untreated. In the Americas, a chronic indolent interstitial keratitis may also occur. Topical steroids are of little use in keratitis (systemic antileishmanials being the cornerstone of treatment). However, these are essential in cases of uveitis, with or without concomitant systemic antileishmanial therapy. In conclusion, though ocular involvement in Leishmaniasis is rare, severe sight-threatening consequences follow if left untreated. Early diagnosis, enthusiastic follow-up and aggressive treatment are essential for good outcomes.

Liposomal amphotericin B is more effective in polymorphic lesions of post kala-azar dermal leishmaniasis

BACKGROUND

Post kala-azar dermal leishmaniasis (PKDL) is thought to be the reservoir of infection for visceral leishmaniasis in South Asia. The development of strategies for the diagnosis and treatment of PKDL are important for the implementation of the visceral leishmaniasis elimination program.

AIMS

Liposomal amphotericin B (L-AMB) has been an overwhelming success in the treatment of visceral leishmaniasis. However, the empirical three-week regimen of L-AMB proposed for PKDL was shown to be inadequate, especially in the macular variant. This study aimed to delineate response of the different variants of PKDL to L-AMB.

METHODS

Skin biopsies were collected from PKDL cases at disease presentation and upon completion of treatment with L-AMB. Parasite DNA was detected by Internal Transcribed Spacer-1 PCR (ITS-1 PCR) and quantified by amplification of parasite kDNA. CD68 + macrophages were estimated in tissue sections by immunohistochemistry.

RESULTS

Treatment with L-AMB decreased the parasite load by 97% in polymorphic cases but only by 45% in macular cases. The median parasite load (89965 vs 5445 parasites/μg of genomic DNA) as well as infiltration by CD68+ cells before treatment was much greater in the polymorphic cases.

LIMITATIONS

Although monitoring of the parasite load for 12 months post-treatment would have been ideal, this was not possible owing to logistical issues as well as the invasive nature of biopsy collection procedure.

CONCLUSION

A dramatic decrease in the parasite burden was noted in patients with polymorphic lesions. Although patients with macular disease also had a decrease in parasite burden, this was not as marked as in the polymorphic cases. There was also a significantly greater infiltration of CD68 + macrophages in polymorphic PKDL before therapy.

Real-Time Fluorimetry Loop-Mediated Isothermal Amplification for Diagnosis of Leishmaniasis and as a Tool for Assessment of Cure for Post-Kala-Azar Dermal Leishmaniasis

Despite the dwindling number of visceral leishmaniasis (VL) cases in India, there is an urgent need for early and unequivocal diagnostics for controlling and preventing the reemergence of VL. Post-kala-azar dermal leishmaniasis (PKDL), a dermal sequela of VL, serves as a reservoir of the parasite. Diagnosis of PKDL, especially the macular variant, is challenging and poses impediment toward attainment of VL elimination. In this study, a real-time fluorimetry loop-mediated isothermal amplification (RealAmp) assay has been established for the detection of different clinical manifestations of leishmaniasis. The study included 150 leishmaniasis patients (25 VL, 25 cutaneous leishmaniasis [CL], and 100-PKDL) along with 120 controls. The assay demonstrated sensitivity of 100% (95% CI: 86.68-100) for diagnosis of VL and PKDL (95% CI: 79.61-100) and 96% (95% CI: 86.68-100) for CL with 100% specificity. Moreover, considering the cardinal role of PKDL, diagnosis using minimally invasive slit aspirate was explored, which demonstrated remarkable sensitivity of 96% (95% CI: 87.64-98.47). As a test of cure for PKDL, RealAmp successfully detected parasite in two of posttreatment cases who later reported relapse on follow-up. Also, direct sample lysis using slit aspirate was attempted in a small group that yielded sensitivity of 89% (95% CI: 67.20-96.90). RealAmp depicted excellent diagnostic accuracy in the diagnosis of leishmaniasis in concordance with the established SYBR Green I-based visual loop-mediated isothermal amplification (LAMP) and the reference comparator real-time PCR. The study endorsed the employment of LAMP either as visual-LAMP or RealAmp for an accurate and expeditious diagnosis of PKDL and as a tool for assessment of cure.

Safety and immunogenicity of ChAd63-KH vaccine in post-kala-azar dermal leishmaniasis patients in Sudan

Post-kala-azar dermal leishmaniasis (PKDL) is a chronic, stigmatizing skin condition occurring frequently after apparent clinical cure from visceral leishmaniasis. Given an urgent need for new treatments, we conducted a phase IIa safety and immunogenicity trial of ChAd63-KH vaccine in Sudanese patients with persistent PKDL. LEISH2a (ClinicalTrials.gov: NCT02894008) was an open-label three-phase clinical trial involving sixteen adult and eight adolescent patients with persistent PKDL (median duration, 30 months; range, 6-180 months). Patients received a single intramuscular vaccination of 1 × 10¹⁰ viral particles (v.p.; adults only) or 7.5 × 10¹⁰ v.p. (adults and adolescents), with primary (safety) and secondary (clinical response and immunogenicity) endpoints evaluated over 42-120 days follow-up. AmBisome was provided to patients with significant remaining disease at their last visit. ChAd63-KH vaccine showed minimal adverse reactions in PKDL patients and induced potent innate and cell-mediated immune responses measured by whole-blood transcriptomics and ELISpot. 7/23 patients (30.4%) monitored to study completion showed >90% clinical improvement, and 5/23 (21.7%) showed partial improvement. A logistic regression model applied to blood transcriptomic data identified immune modules predictive of patients with >90% clinical improvement. A randomized controlled trial to determine whether these clinical responses were vaccine-related and whether ChAd63-KH vaccine has clinical utility is underway.

A Multi-Country, Single-Blinded, Phase 2 Study to Evaluate a Point-of-Need System for Rapid Detection of Leishmaniasis and Its Implementation in Endemic Settings

With the advancement of isothermal nucleic acid amplification techniques, detection of the pathogenic DNA in clinical samples at point-of-need is no longer a dream. The newly developed recombinase polymerase amplification (RPA) assay incorporated in a suitcase laboratory has shown promising diagnostic efficacy over real-time PCR in detection of leishmania DNA from clinical samples. For broader application of this point-of-need system, we undertook a current multi-country diagnostic evaluation study towards establishing this technique in different endemic settings which would be beneficial for the ongoing elimination programs for leishmaniasis. For this study purpose, clinical samples from confirmed visceral leishmaniasis (VL) and post-kala-azar dermal leishmaniasis (PKDL) patients were subjected to both real-time PCR and RPA assay in Bangladesh, India, and Nepal. Further skin samples from confirmed cutaneous leishmaniasis (CL) patients were also included from Sri Lanka. A total of 450 clinical samples from VL patients, 429 from PKDL patients, 47 from CL patients, and 322 from endemic healthy/healthy controls were under investigation to determine the diagnostic efficacy of RPA assay in comparison to real-time PCR. A comparative sensitivity of both methods was found where real-time PCR and RPA assay showed 96.86% (95% CI: 94.45–98.42) and 88.85% (95% CI: 85.08–91.96) sensitivity respectively in the diagnosis of VL cases. This new isothermal method also exhibited promising diagnostic sensitivity (93.50%) for PKDL cases, when a skin sample was used. Due to variation in the sequence of target amplicons, RPA assay showed comparatively lower sensitivity (55.32%) than that of real-time PCR in Sri Lanka for the diagnosis of CL cases. Except for India, the assay presented absolute specificity in the rest of the sites. Excellent concordance between the two molecular methods towards detection of leishmania DNA in clinical samples substantiates the application of RPA assay incorporated in a suitcase laboratory for point-of-need diagnosis of VL and PKDL in low resource endemic settings. However, further improvisation of the method is necessary for diagnosis of CL.

Cutaneous and Mucocutaneous Leishmaniasis

Leishmaniasis is a chronic disease caused by flagellate protozoa of the genus Leishmania. It is a global disease, but most cases are seen in South America, the Mediterranean, and some areas of Asia and Africa. The 3 main types of leishmaniasis are cutaneous (the most common), mucocutaneous, and visceral (the most severe). Visceral leishmaniasis is also known as kala-azar. Leishmaniasis is diagnosed by demonstrating the presence of Leishmania amastigotes in clinical specimens using direct microscopic examination or molecular analysis. Various treatments exist, although the evidence supporting the options available for cutaneous leishmaniasis is weak. Both the classical presentation of leishmaniasis and our management of the disease have changed in recent decades because of acquired immune deficiency caused by conditions such as HIV infection or the use of TNF inhibitors.

Molecular Tracking of the Leishmania Parasite

With the Visceral Leishmaniasis/Kala-azar Elimination Program in South Asia in its consolidation phase, the focus is mainly on case detection, vector control, and identifying potential sources of infection. Accordingly, emphasis is presently on curbing transmission, which is potentially achievable by identification and elimination of potential reservoirs. The strongest contenders for being the disease reservoir are cases of Post Kala-azar Dermal Leishmaniasis (PKDL) which occurs in a minor proportion of individuals apparently cured of Visceral Leishmaniasis (VL). The demonstration of parasites in tissue aspirates despite being a risky and invasive process is the gold standard for diagnosis of VL, but is now being replaced by serological tests e.g., rK39 strip test and direct agglutination test. However, these antibody based tests are limited in their ability to diagnose relapses, detect cases of PKDL, and monitor effectiveness of treatment. Accordingly, detection of antigen or nucleic acids by polymerase chain reaction has been successfully applied for monitoring of parasite kinetics. This review article provides updated information on recent developments regarding the available antibody or antigen/nucleic acid based biomarkers for longitudinal monitoring of patients with VL or PKDL and emphasizes the need for availability of studies pertaining to quantification of treatment response or relapse.

Atypical Presentation of Post-Kala-Azar Dermal Leishmaniasis in Bhutan

This article describes an atypical case of post-kala-azar dermal leishmaniasis associated with complications due to delayed diagnosis and poor case management. The grave consequences of the prolonged disease process that continued for over 2 decades with eventual healing included facial disfigurement, visual impairment, and mental distress both to the patient and the family. The persistent infection within the skin over a lengthy period with likely increased risk of infection spread in the community highlights its potential negative impact on the ongoing leishmaniasis elimination program in the Indian subcontinent. Bhutan is a member of the leishmaniasis elimination network in Asia, and the government continues to invest in maintenance of the national healthcare system. The case study reveals the gaps in the healthcare system with hardships faced by a patient to access quality healthcare and poor patient outcome used as proxy indicators. It also points to the need to enhance access to healthcare to ensure early diagnosis and effective treatment for leishmaniasis patients including those who live in remote areas, in order to achieve the planned disease elimination targets. It also points towards the key challenges faced by a resource poor nation such as Bhutan in achieving universal health coverage and reaching the set goals for disease elimination. The findings underscore the need for a careful review of the national health care system and to address the deficiencies.

DNA-based microarray studies in visceral leishmaniasis: identification of biomarkers for diagnostic, prognostic and drug target for treatment

Visceral leishmaniasis (VL) is one of the major infectious diseases affecting the poorest regions of the world. Current therapy is not very much satisfactory. The alarming rise of drug resistance and the unavailability of an effective vaccine against VL urges research towards identifying new targets or biomarkers for its effective treatment. New technology developments offer some fresh hope in its diagnosis, treatment, and control. DNA microarray approach is now broadly used in parasitology research to facilitate the thoughtful of mechanisms of disease and identification of drug targets and biomarkers for diagnostic and therapeutic development. An electronic search on "VL" and "Microarray" was conducted in Medline and Scopus and papers published in the English mentioning use of DNA microarray on VL were selected and read to write this paper review. Functional analysis and interpretation of microarray results remain very challenging due to the inherent nature of experimental workflows, access, cost, and complexity of data obtained. We have explained and emphasized the use of curate knowledge of microarray in the case of VL for the identification of therapeutic target and biomarker and their selection/implementation in clinical use.

Post kala-azar dermal leishmaniasis: A threat to elimination program

Leishmaniasis remains a public health concern around the world that primarily affects poor folks of the developing world spanning across 98 countries with mortality of 0.2 million to 0.4 million annually. Post kala-azar dermal leishmaniasis (PKDL) is the late skin manifestation of visceral leishmaniasis (VL). It has been reported that about 2.5% to 20% of patients recovered from VL develop PKDL having stilted macular or nodular lesions with parasites. In the Indian subcontinent (ISC), it manifests a few months after recovery from VL, though in Africa it can occur simultaneously with VL or a little later. New cases of PKDL are also observed without prior VL in the ISC. These individuals with PKDL represent an important but largely neglected reservoir of infection that perpetuates anthroponotic Leishmania donovani transmission in the ISC and can jeopardize the VL elimination program as these cases can infect the sand flies and spread the endemic. Therefore, it becomes imperative to eradicate PKDL as a part of the VL elimination program. With the limited treatment options besides little knowledge on PKDL, this review stands out in focusing on different aspects that should be dealt for sustained VL elimination.

Leishmaniasis immunopathology-impact on design and use of vaccines, diagnostics and drugs

Leishmaniasis is a disease complex caused by 20 species of protozoan parasites belonging to the genus Leishmania. In humans, it has two main clinical forms, visceral leishmaniasis (VL) and cutaneous or tegumentary leishmaniasis (CL), as well as several other cutaneous manifestations in a minority of cases. In the mammalian host Leishmania parasites infect different populations of macrophages where they multiply and survive in the phagolysosomal compartment. The progression of both VL and CL depends on the maintenance of a parasite-specific immunosuppressive state based around this host macrophage infection. The complexity and variation of immune responses and immunopathology in humans and the different host interactions of the different Leishmania species has an impact upon the effectiveness of vaccines, diagnostics and drugs.

New Strategies and Biomarkers for the Control of Visceral Leishmaniasis

Effective diagnosis and treatment of visceral leishmaniasis, together with the study of vectors and reservoirs, can lead to a better understanding of the parasite transmission dynamics and the development of more efficient control measures. Recent studies have applied new methodologies and biomarkers, and these have contributed to the early and rapid diagnosis of the disease; assessment of success of pharmacological treatments; efficient monitoring of immunosuppressed individuals; and to population screening for field trials of vaccine efficacy. This opinion article proposes an update to the diagnostic tools for visceral leishmaniasis and their rational and combined use to establish the real prevalence of infection or of exposure to Leishmania in endemic areas.